Apparatus for correcting strains in stamp-forgings

ABSTRACT

This invention relates to an apparatus for correcting strains in such stamp-forgings as, for example, front axles with one stroke of a press without requiring skilled labors and without requiring an additional step for each bend of heat-treated products.

ljmted States Patent 1 1 9 9 Numoto et al. 0st. 9., 19731 [54] APPARATUS FOR CORRECTING STRAINS 1,299,292 4/1919 Borkey 72/302 IN STAMP FORGINGS 3,349,598 11/1967 Pollak 72/302 [75] Inventors: Yasumasa Numoto, Yao; Kyuhei Ita N b th f J am 0 o apan Primary ExaminerLowell A. Larson [73] Assignee: Sumitomo Metal Industries Limited, Attorney-Watson, Cole, Grindle & Watson Osaka City, Japan [22] Filed: Mar. 14, 1972 21 A 1. No.: 234 622 i 1 pp 57 ABSTRACT [52] US. Cl 72/392, 72/378, 72/395 51 Int. Cl B21j 13/02 T1115 "Wemm relates an apparatus for cofrectmg 581 Field of Search 72/302, 378, 392, Strains in Such Stamp-wings as, for example, from 72/395, 148/130 131 axles with one stroke of a press without requiring skilled labors and without requiring an additional step [56] References Cited for each bend of heabtreated products.

UNITED STATES PATENTS 2,003,127 5/1935 Vaughan 72/378 3 Claims, 3 Drawing Figures PATENIEU Hill 9 I975 SHUT 1 UP 2 FIG.

J I l I I APPARATUS FOR CORRECTING STRAINS IN STAMP-FORGINGS This invention relates to an apparatus for correcting strains in stamp-forgings Generally strains in stamp-forgings are composed of bends, twists and shrinks and it is considered difficult to remove and correct them. Further, the fluctuation of the finished dimensions and shapes after the correction is so great that a considerable skill has been required to attain unity of the finished dimensions and shapes of stamp-forgings.

An object of the present invention is to provide an apparatus for correcting strains in stamp-forgings which are particularly large in the length as compared with the cross-section, wherein the above-mentioned defects are eliminated by holding and stretching a stamp-forging with upper dies pressed down onto lower dies bridging and supporting the stamp-forging by utilizing residual heat after the heat-treatment.

Another object of the present invention is to provide an apparatus for achieving an efficient operation without requiring a technical skill, and wherein lower dies are opposed to each other and are mounted on the upper surface of a lower bolster, end upper dies having reaction absorbing devices interposed being slidably opposed to each other and being suspended on the lower surface of an upper bolster, and a pressing die wedged between the opposed surfaces of the end upper and lower dies.

In the drawings:

FIGS. 1 and 2 show an apparatus according to the presentinvention respectively before and during the operation, the right half being an elevation and the left half being a sectioned view;

FIG. 3 is a sectioned view taken on line llIlII in FIG. 2.

Referring to FIGS. 1 and 2, end lower dies 3 are slidably mounted as fitted in grooves 2 on a lower bolster 1, and end upper dies are slidably suspended as having a suspending clearance D on the lower surface of an upper bolster 4 having a loading device (not illustrated). Accordingly the end upper and lower dies 5 and 3 may hold and press both end'parts 8 of a forging 6 from above and below without interfering with the intermediate part thereof, and may be fitted together to be integrally opposed toeach other by providing die fitting knock pins 9 and 10 or the like. The opposed surfaces 11 of the end upper and lower dies 5 and 3 converge gradually toward lower bolster 1 soas to be used as wedging surfaces for the hereinafter described pressing die. Therefore, the end lower dies. 3 and end upper dies 5 are normally provided with sloped surfaces respectively on the opposed surfaces.

The illustrated embodiment is to correct strains in a front axle for an automobile, which axle constitutes the above-described stamp-forging. The front axle is held by the end upper and lower dies 5 and 3 in both end parts 8 from the right and left spring seats to the kingpin bosses and its intermediate part 7 bridges between pressure devices 14 and presses the end upper dies 5 onto the end lower dies 3. In such case, the upper bolster 4 will be stopped by the end lower dies 3 from lowering but, if the depression exceeds an adjusted fixed pressure of the pressure accumulators 13, the reaction of the end upper dies 5 against the force of lowering the upper bolster 4 will be absorbed by the pressure accumulators 13 and the upper bolster 4 will lower further. In order to thus interpose the reaction absorbing devices 12 between the upper bolster 4 and end upper dies 5, instead of the above-mentioned liquid pressure devices 14, compression springs may be provided to project on the upper bolster 4 so as to contact the upper surfaces of the end upper dies 5. A pressing die 16, disposed to project between the opposed end upper dies 5 on the lower surface of the upper bolster 4, has wedging surfaces 17 converging toward lower bolster 1 so as to be conveniently wedged in between both opposed surfaces 11 of the end upper and lower dies 5 and 3 placed on each other. Pressing die 16 is provided with a recessed part 18 to avoid interference with the bridged intermediate part 7 of the stamp-forging 6 when the pressing die 16 is wedged in.

Now, while the stamp-forging 6 is likely to be deformed by residual heat after such heat-treatment as by quenching or annealing, the end upper dies 5 and pressing die 16 are elevated with the upper bolster 4 and separated from the end lower dies 3. The end parts 8 of the stamp-forging 6 are mounted on the end lower dies 3 and the stamp-forging bridges these lower dies. the intermediate When the upper bolster 4 is then loaded for lowering, the end upper dies 5 will be placed on the end lower dies 3, will be fitted to them with the knock pins 9 and 10 or the like and will be pressed on them through the reaction absorbing devices 12 so that the stamp-forging 6 may be held and pressed at both end parts 8. The end upper and lower dies 5 and 3, are positively chucked and any deformation in theintermediate part 7 of stamp-forging 6 is corrected.

When the load on the upper bolster 4 exceeds the set pressure of the reaction absorbing devices 12, the reaction absorbing devices 12 will operate and, the rams 15 will retreat as shown in the drawing to absorb the reaction of the end upper dies 5. Therefore, the pressing'die 16 will lower by the depressed distance d to reach the chain line illustration shown in the left half of FIG. 2 and will be wedged in between the opposed surfaces 11 of the end upper and lower dies 5 and 3. Therefore, the end upper and lower dies 5 and 3 will slide between the upper and lower bolsters 4 and 1 so as to expand to the chain line position shown in the left half of FIG. 2, and the forging 6 will also stretch to the chain line position 19 and will be pastically deformed so that any bend and twist of the intermediate part 7 may be corrected. The suspending clearance D of the above-described end upper dies 5 is determined to be equal to or larger than the depressing distance d. it is needless to say that, even while the pressing die is being wedged in, the reaction absorbing devices 12 will press the end upper dies 5 with a fixed pressure.

The above-mentioned operation is made by one stretched to a fixed value and will be corrected.

Then, if the upper bolster 4 is elevated and the stamp-forging 6 is taken out, it will have a desired fixed length and will have any bend and twist removed, that is, will be corrected. As the forging at the abovedescribed temperature is air-cooled as it is, even after it reaches the normal temperature, the effect of the correction will be maintained as is.

In a known technique for correcting strains in such stamp-forging as, for example, a front axle, each bend of the heat-treated finished product is removed with a bender, or the product is heated to be quenched. Any strain is corrected with a quenching press, is put into a quenching liquid as held with the quenching press is, then taken out from the quenching press and is then tempered. However, since the operation is carried out by hand, efficiency is not only low but the fluctuation of the finished dimensions and shapes depends on the skill of the operator. Defects have resulted using this known technique in that, as the residual stress at the time of quenching is produced in the front axle in a defined shape, when it is taken out from the quenching press and is tempered, the strain corrected at the time of quenching it will again occur.

In the method according to the present invention, as the stamp-forging is plastically deformed by utilizing residual heat after tempering and is air-cooled, in the case of plastically deforming the stamp-forging at a temperature of 400 to 600C. (in the case of a carbon steel), the force required for the deformation will be smaller than in the case of the normal temperatuee and a larger amount of deformation will be able to be obtained. As the relation between the end upper and lower dies 5 and 3 and the pressing die 16 is constant, the finished dimensions and shapes will be uniform without depending on the skill of the operator, and all the strains will be corrected efficiently with one stroke of the upper bolster 4. Such stamp-forging is quite favorable for a great length as compared to its crosssectional area when the shape of the central part is simple and straight as for a front axle.

Also, depending on the material of the stamp-forging, the temperature at the time of correcting it may be either higher or lower than the above-mentioned value of 400 to 600C. considered proper in the case of a carbon steel.

We claim:

1. An apparatus for correcting strains in stampforging members, comprising a lower bolster member, end lower dies slideably mounted on the upper surface of said lower bolster member for movement away from one another, an upper bolster member, end upper dies slideably suspended from said upper bolster member for movement away from one another, said dies together supporting the stamp-forging member at its opposite ends, reaction absorbing devices on each of said end upper dies, opposing surfaces at the inner ends of said respective end lower dies and said end upper dies converging toward said lower bolster member, and a pressing die member projecting between said respective opposing surfaces, said pressing die member having opposed surfaces converging toward said lower bolster member and mating with said die opposing surfaces so as to be wedged therebetween, whereby said pressing die member causes said respective end upper dies and said end lower dies to move away from one another while the strains in the stamp-forging member are being corrected during a heating operation.

2. An apparatus for correcting strains in stampforging members according to claim 1 wherein said reaction absorbing device has a liquid pressure device having a pressure accumulator and a ram. I

3. An apparatus for correcting strains in stampforging members according to claim 1 wherein said pressing die is provided with a recessed part provided so that said pressing die does not interfere with the intermediate part of the stamp-forging member. 

1. An apparatus for correcting strains in stamp-forging members, comprising a lower bolster member, end lower dies slideably mounted on the upper surface of said lower bolster member for movement away from one another, an upper bolster member, end upper dies slideably suspended from said upper bolster member for movement away from one another, said dies together supporting the stamp-forging member at its opposite ends, reaction absorbing devices on each of said end upper dies, opposing surfaces at the inner ends of said respective end lower dies and said end upper dies converging toward said lower bolster member, and a pressing die member projecting between said respective opposing surfaces, said pressing die member having opposed surfaces converging toward said lower bolster member and mating with said die opposing surfaces so as to be wedged therebetween, whereby said pressing die member causes said respective end upper dies and said end lower dies to move away from one another while the strains in the stamp-forging member are being corrected during a heating operation.
 2. An apparatus for correcting strains in stamp-forging members according to claim 1 wherein said reaction absorbing device has a liquid pressure device having a pressure accumulator and a ram.
 3. An apparatus for correcting strains in stamp-forging members according to claim 1 wherein said pressing die is provided with a recessed part provided so that said pressing die does not interfere with the intermediate part of the stamp-forging member. 